The anti-microbial properties of ultraviolet violet-C (UV-C) light are well-known to scientists and have been used since the 1930's to kill germs containing DNA and RNA (including bacteria, viruses, fungi, and mold). UV-C light is invisible to the human eye. While UV-C light is invisible, given sufficient intensity and exposure, UV-C light can kill most of the germs responsible for causing disease in humans and animals. UV-C light can destroy the DNA and/or RNA (genetic material) of pathogens (disease-causing bacteria, viruses, mold, etc.). Once the DNA in a pathogen has been destroyed, the pathogen is either killed or deactivated. At that point, the pathogen can no longer function properly; and the pathogen can no longer reproduce.
In general, ultraviolet (UV) light is classified into three wavelength ranges: UV-C, from about 200 nanometers (nm) to about 280 nm; UV-B, from about 280 nm to about 315 nm; and UV-A, from about 315 nm to about 400 nm. Generally, ultraviolet light, and in particular, UV-C light is “germicidal,” i.e., it deactivates the DNA of bacteria, viruses and other pathogens and thus destroys their ability to multiply and cause disease. This effectively results in sterilization of the microorganisms. Specifically, UV-C light causes damage to the nucleic acid of microorganisms by forming covalent bonds between certain adjacent bases in the DNA. The formation of these bonds prevents the DNA from being “unzipped” for replication, and the organism is neither able to produce molecules essential for life process, nor is it able to reproduce. In fact, when an organism is unable to produce these essential molecules or is unable to replicate, it dies. UV light with a wavelength of approximately between about 250 to about 280 nm provides the highest germicidal effectiveness. While susceptibility to UV light varies, exposure to UV energy for about 20 to about 34 milliwatt-seconds/cm2 is adequate to deactivate approximately 99 percent of the pathogens.
Box-type UV sterilizers are well known for use in sterilizing all different objects including contact lenses, combs and safety goggles. With these types of sterilizers, only a single source of radiation is usually employed and, as such, there are often areas on an object to be sterilized that are shadowed from the UV radiation produced from the single source. Furthermore, the object to be sterilized is often required to rest on a support during the sterilization process. If the support is not transparent to the UV radiation, the support also contributes to shadowing the object to be sterilized from the UV radiation.
Various approaches have been used in decontaminating surfaces through the use of ultraviolet light. For example, in one approach, a mobile germicidal system for decontaminating walls and a ceiling of a room is disclosed. Germicidal lamps are positioned adjacent the wall and/or ceiling to thereby sterilize the surface. Another approach discloses an ultraviolet air sterilization device for connection to an air handling duct for the purpose of sterilizing the air as it flows through the duct. Another approach discloses a wheeled carriage with a handle to allow the operator to move the sterilization device over a floor.
An apparatus using ultraviolet light is disclosed in one approach for treating an object. A handheld device for moving across a surface to eradicate undesirable elements thereon is disclosed in another approach. An additional approach discloses a mobile disinfectant device and method using ultraviolet light to sterilize a surface. Another approach provides a UV spot curing system for hardening epoxy material using a wand emitting ultraviolet light.